Methods and systems for determining physiologic characteristics for treatment of the esophagus

ABSTRACT

A system for measuring physiologic characteristics for treating abnormal mucosa in the esophagus comprises a sizing device having an inflatable balloon on a distal end of a catheter that is inflated with an expansion medium to expand the balloon to engage the wall of the esophagus so that the internal cross-section can be calculated or measured. The sizing device may also include an infusion source for delivering the expansion medium and means for measuring the amount and pressure of the expansion medium inside the catheter. The system also comprises one or more energy delivery devices for injuring or ablating the esophageal tissue.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No.10/754,452; filed Jan. 9, 2004, now abandoned, which is acontinuation-in-part of commonly assigned, U.S. patent application Ser.No. 10/370,645, filed Feb. 19, 2003, now U.S. Pat. No. 7,530,979, whichis a divisional of Ser. No. 09/714,344, filed Nov. 16, 2000, now U.S.Pat. No. 6,551,310, which claims the benefit under 35 USC 119(e) of U.S.Provisional Application No. 60/165,687 filed Nov. 16, 1999, the fulldisclosure of which are fully incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to medical methods and systems.More particularly, the invention is directed to methods and systems fortreating and determining physiologic characteristics of body lumens suchas the esophagus.

The human body has a number of internal body lumens or cavities locatedwithin, many of which have an inner lining or layer. These inner liningscan be susceptible to disease. In some cases, surgical intervention canbe required to remove the inner lining in order to prevent the spread ofdisease to otherwise healthy tissue located nearby.

Those with persistent problems or inappropriate relaxation of the loweresophageal sphincter can develop a condition known as gastroesophagealreflux disease, manifested by classic symptoms of heartburn andregurgitation of gastric and intestinal content. The causative agent forsuch problems may vary. Patients with severe forms of gastroesophagealreflux disease, no matter what the cause, can sometimes developsecondary damage of the esophagus due to the interaction of gastric orintestinal contents with esophageal cells not designed to experiencesuch interaction.

The esophagus is composed of three primary tissue layers; a superficialmucosal layer lined by squamous epithelial cells, a middle submucosallayer and a deeper muscle layer. When gastroesophageal reflux occurs,the superficial squamous epithelial cells are exposed to gastric acid,along with intestinal bile acids and enzymes. This exposure may betolerated, but in some cases can lead to damage and alteration of thesquamous cells, causing them to change into taller, specialized columnarepithelial cells. This metaplastic change of the mucosal epithelium fromsquamous cells to columnar cells is called Barrett's esophagus, namedafter the British surgeon who originally described the condition.

Barrett's esophagus has important clinical consequences, since theBarrett's columnar cells can, in some patients, become dysplastic andthen progress to a certain type of deadly cancer of the esophagus. Thepresence of Barrett's esophagus is the main risk factor for thedevelopment of adenocarcinoma of the esophagus.

Accordingly, attention has been focused on identifying and removing thisabnormal Barrett's columnar epithelium in order to mitigate more severeimplications for the patient. Devices and methods for treating abnormalbody tissue by application of various forms of energy to such tissuehave been described, such as radio frequency ablation. However, withoutprecise control of the depth of penetration of the energy means, thesemethods and devices are deficient. Uncontrolled energy application canpenetrate too deeply into the esophageal wall, beyond the mucosa andsubmucosal layers, into the muscularis externa, potentially causingesophageal perforation, stricture or bleeding. Accordingly, properadministration of the correct amount of treatment energy to the tissuecan be facilitated by knowledge of the size of the esophagus and area tobe treated.

Additionally, medical procedures for treating Barrett's esophagustypically involve deployment of an expandable catheter inside theesophagus. Expandable catheters are preferred because the profile of thecatheter is ideally as small as possible to allow for ease of delivery,while treatment of the esophagus is most efficiently performed when thecatheter is at or slightly larger than the diameter of the esophagealwall. Proper sizing and/or pressurization of the delivery device istherefore desirable to prevent over-distension of the organ, which couldresult in harm to the organ, or under-expansion of the catheter, whichoften results in incomplete treatment. Accordingly, accurate and simplemeasurement of the size of the lumen and control of the pressure of thecatheter on the lumen surface promotes the proper engagement anddelivery of energy to the luminal wall so that a uniform and controlleddepth of treatment can be administered. In addition to calculatingluminal dimensions, the compliance of the lumen can be determined bymeasuring the cross section of the lumen at two or more pressure values.

Therefore, it would be advantageous to have methods and systems foraccurately determining in vivo the size and optionally the compliance ofa body lumen such as the esophagus. In addition, it would be desirableto provide a method and system for treating the body lumen once havingdetermined its size. At least some of these objectives will be met bythe present invention.

2. Description of the Background Art

U.S. Pat. No. 5,275,169 describes apparatus and methods for determiningphysiologic characteristics of blood vessels. The device measures thediameter and wall compliance of the blood vessel, and does notadminister treatment. Additionally, the method relies on using only anincompressible fluid to inflate a balloon inside a blood vessel. Otherpatents of interest include U.S. Pat. Nos. 6,010,511; 6,039,701; and6,551,310.

BRIEF SUMMARY OF THE INVENTION

The present invention comprises methods and systems for sizing a bodylumen, such as the esophagus. Methods and systems are also provided fortreating the body lumen once the proper measurements have been made.

Although the following description will focus on embodiments configuredfor treatment of the esophagus, other embodiments may be used to treatany other suitable lumen in the body. In particular, the methods andsystems of the present invention may be used whenever accuratemeasurement of a body lumen or uniform delivery of energy is desired totreat a controlled depth of tissue in a lumen or cavity of the body,especially where such body structures may vary in size. Therefore, thefollowing description is provided for exemplary purposes and should notbe construed to limit the scope of the invention.

In one aspect of the invention, a method for treating a body lumen at atreatment location comprises measuring a luminal dimension at thetreatment location of the lumen, selecting an electrode deploymentdevice having an array of electrodes or other electrode structure with apre-selected deployed size which corresponds to the measured dimension,positioning the electrode deployment device at the treatment locationwithin the lumen, deploying the electrode array to the pre-selecteddeployed state to engage a wall of the lumen, and delivering energy tothe electrodes for treatment of the luminal tissue.

In some embodiments, measuring the luminal dimension comprisespositioning a sizing member at the treatment location within the lumen,expanding the sizing member until it engages an inside wall of thelumen, and calculating the luminal dimension at the treatment locationof the esophagus based on the expansion of the sizing member. Often,expanding the sizing member comprises inflating a sizing balloon byintroducing an expansion medium. The expansion medium may be acompressible or non-compressible fluid. In some embodiments, the lumendimensions are calculated by determining the amount of the expansionmedium introduced to the sizing balloon while it is inflated. Forexample, the mass or volume of the expansion medium can be measured byuse of a mass-flow meter or the like. Optionally, a pressure sensor maybe coupled to the sizing balloon, so that the luminal dimension can becalculated from the measured amount of expansion medium introduced tothe balloon at a given pressure. Alternatively, the sizing member maycomprise a basket, plurality of struts, or calipers, or the like. Thelumen may also be measured by ultrasound, optical, or fluoroscopicimaging or by use of measuring strip.

In embodiments where a sizing balloon is employed, the sizing balloonmay comprise any material or configuration. In general, the sizingballoon is cylindrical and has a known length and a diameter that isgreater than the diameter of the target lumen. In this configuration,the sizing balloon is non-distensible, such as a bladder having adiameter in its fully expanded form that is larger than the lumendiameter. Suitable materials for the balloon may comprise a polymer suchas polyimide or polyethylene terephthalate (PET). Alternatively, theballoon may comprise an elastomer or mixture of polymers and elastomers.

Once the lumen dimensions are determined, an electrode deployment devicematching the measured luminal dimension may be selected from aninventory of devices having different electrode deployment sizes. Insome embodiments, the electrode deployment device is transesophageallydelivered to a treatment area within the esophagus. For example,delivering the device may be facilitated by advancing a catheter throughthe esophagus, wherein the catheter carries the electrode array and anexpansion member. The expansion member may comprise any of the materialsor configurations of the sizing member, such as an inflatablecylindrical balloon comprising a polymer such as polyimide or PET.

In some aspects of the invention, the array of electrodes or otherelectrode structure are arranged on a surface of a dimensionally stablesupport such as a non-distensible, electrode backing. The backing maycomprise a thin, rectangular sheet of polymer materials such aspolyimide, polyester or other flexible thermoplastic or thermosettingpolymer film, polymer covered materials, or other nonconductivematerials. The backing may also comprise an electrically insulatingpolymer, with an electro-conductive material, such as copper, depositedonto a surface. For example, an electrode pattern can be etched into thematerial to create an array of electrodes. The electrode pattern may bealigned in an axial or traverse direction across the backing, formed ina linear or non-linear parallel array or series of bipolar pairs, orother suitable pattern. In many embodiments, delivering energy comprisesapplying radiofrequency (RF) energy to tissue of the body lumen throughthe electrodes. Depending on the desired treatment effect, theelectrodes may be arranged to control the depth and pattern oftreatment. For treatment of esophageal tissue, the electrode widths areless than 3 mm, typically a width in the range from 0.1 mm to 3 mm,preferably 0.1 mm to 0.3 mm, and adjacent electrodes are spaced apartless than 3 mm, typically in the range from 0.1 mm to 3 mm, preferablyfrom 0.1 mm to 0.3 mm. Alternatively, energy may be delivered by use ofstructures other than those having an array of electrodes. For example,the electrode structure may comprise a continuous electrode arranged ina helical pattern over the balloon.

In another method of the present invention, the measurement of theluminal dimension may be used to determine the amount of energydelivered to the tissue of the lumen. For example, a method for treatingthe tissue of a body lumen at a treatment location comprises measuring aluminal dimension at a location of the lumen, positioning an electrodedeployment device at that location, deploying the expansion member toengage an electrode array to a wall of the lumen; and deliveringsufficient energy to the electrode array for treatment of the luminaltissue based on the measured dimension of the lumen. In general, theamount of power delivered to the electrodes will vary depending on thetype of treatment and the overall surface area of the luminal tissue tobe treated. In some embodiments, the expansion member can variablyexpand to engage the wall of the lumen independent of the size of thelumen. For esophageal treatment, the expansion member may comprise aballoon that can expand to a range of diameters between 12 mm and 50 mm.Typically, the total energy density delivered to the esophageal tissuewill be in the range from 1 J/cm2 to 50 J/cm2, usually being from 5J/cm2 to 15 J/cm2. In order to effectively ablate the mucosal lining ofthe esophagus and allow re-growth of a normal mucosal lining withoutcreating damage to underlying tissue structures, it is preferable todeliver the radiofrequency energy over a short time span in order toreduce the effects of thermal conduction of energy to deeper tissuelayers, thereby creating a “searing” effect. It is preferable to deliverthe radiofrequency energy within a time span of less than 5 seconds. Anoptimal time for effective treatment is less than 1 second, andpreferably less than 0.5 second or 0.25 seconds. The lower bound on timemay be limited by the ability of the RF power source to deliver highpowers.

In one aspect of the invention, a method for measuring an internaldimension at a location in a body lumen comprises positioning acylindrical balloon at a location within the lumen, inflating theballoon with an expansion medium to engage an inside wall of the lumen,monitoring the extent of engagement of the balloon, determining theamount of expansion medium in the balloon while inflated at thelocation, and calculating the internal dimension of the esophagus basedon the length of the balloon and the measured amount of expansion mediuminside the balloon. In some embodiments, the balloon istransesophageally delivered to a treatment area within the esophagus byadvancing a catheter carrying the balloon through the esophagus. Often,the balloon is non-distensible and has a diameter that is greater thanthe diameter of the inside wall of the lumen. The balloon may be filledwith an expansion medium that is a compressible fluid, such as air.

Monitoring the extent of engagement comprises determining the expansionof the balloon via a pressure sensor coupled to the balloon, wherein theextent of engagement is determined by the internal pressure exerted fromthe expansion medium as measured by the pressure sensor and by visualverification. The pressure sensor may comprise any device fordetermining the pressure inside a vessel, such as a strain gauge.Alternatively, the extent of may be monitored by determining theexpansion of the balloon via visual inspection. In some embodiments, theballoon may be expanded to apply pressure to the inside wall of thelumen, thereby causing the lumen to stretch.

In one aspect of the invention, a method for determining wall complianceof an esophagus comprises positioning a balloon at a location within theesophagus, inflating the balloon with a compressible fluid, measuringthe static pressure within the balloon, measuring the total amount offluid within the balloon at at least two static pressure values, andcalculating the wall compliance based on the variation in the amount offluid between a first measured pressure and a second measured pressure.For esophageal treatment, the static pressure values to be used aretypically below 10 psig, and preferably at or below 7 psig.

In another aspect, a system for treating tissue of a body lumencomprises a sizing member for measuring the cross section at a locationof the lumen and a catheter having a set of individual treatmentdevices, each device comprising an electrode array adapted to treat atarget location, wherein at least some of the arrays are adapted totreat locations having different sizes determined by the sizing member.In some embodiments, the sizing member comprises an inflatable,noncompliant sizing balloon that is oversized with respect to the insidewall of the lumen. The sizing balloon may be cylindrical with a diameterthat is oversized with respect to the inside wall of the lumen. Thesizing balloon may further be coupled to a pressure sensor fordetermining the internal pressure in the balloon from the introductionof the expansion medium. In addition, the system may further comprise ameasuring means, such as a mass flow meter, for determining the amountof fluid in the sizing balloon.

In some embodiments, each of the individual treatment devices furtherinclude an expansion member comprising an inflatable balloon. Generally,each balloon is cylindrical and ranges in diameter from 12 mm to 50 mmwhen expanded. A balloon within the range is selected based on themeasurement made from the sizing balloon so that when the balloon isexpanded to its fully inflated shape, it properly engages the wall ofthe lumen. Typically, the expansion member is inflated with the samemedium as the sizing balloon. Optionally, the treatment device mayfurther include a pressure sensor as an extra precaution againstover-distension of the organ.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of portions of an upper digestive tract in ahuman.

FIG. 2 is a cross sectional view of a device of the invention insertedin to an esophagus in its relaxed, collapsed state.

FIG. 3 is a cross-sectional view of a device of the invention deployedin an expanded configuration in the esophagus.

FIG. 4 is a schematic view of a sizing device of the invention.

FIG. 5 is a flow chart of a method of the invention for sizing a luminaldimension.

FIG. 6 is a flow chart of a method of the invention for treating luminaltissue

FIG. 7 is a chart of test results performed on calculating the diameterof a vessel by measuring the volume of air used to inflate the balloon.

FIG. 8 is a chart of test results for the air mass required to achievevarious pressure levels in differently sized rigid containers.

FIG. 9 is a schematic view of a treatment device of the invention in acompressed configuration in the esophagus.

FIG. 10 is a schematic view of a treatment device of the invention in anexpanded configuration in the esophagus.

FIG. 11 is a schematic view of another embodiment of a treatment deviceof the invention.

FIG. 12 shows a top view and a bottom view of an electrode pattern ofthe device of FIG. 11.

FIG. 13 shows the electrode patterns that may be used with a treatmentdevice of the invention.

FIG. 14 shows additional electrode patterns that may be used with atreatment device of the invention.

FIG. 15 shows a flow chart of a method of the invention for determiningthe wall compliance of a lumen.

DETAILED DESCRIPTION OF THE INVENTION

In various embodiments, the present invention provides methods andsystems for measuring, and treating at a controlled and uniform depth,the inner lining of a lumen within a patient. It will be appreciatedthat the present invention is applicable to a variety of differenttissue sites and organs, including but not limited to the esophagus. Atreatment apparatus including a sizing member and a treatment devicecomprising an expandable electrode array is provided. The sizing memberis first positioned at a treatment site within the lumen. Once in place,the sizing member is expanded to engage the wall of the lumen to obtainthe dimensions of the lumen. The sizing member is removed, and at leasta portion of the treatment device is positioned at the tissue site,where the electrode array is expanded to contact the tissue surfaceaccording to the measurements made by the sizing member. Sufficientenergy is then delivered from the electrode array to impart a desiredtherapeutic effect, such as cell necrosis, to a discreet layer oftissue.

Certain disorders can cause the retrograde flow of gastric or intestinalcontents from the stomach 12, into the esophagus 14, as shown by arrowsA and B in FIG. 1. Although the causation of these problems are varied,this retrograde flow may result in secondary disorders, such asBarrett's Esophagus, which require treatment independent of and quitedifferent from treatments appropriate for the primary disorder—such asdisorders of the lower esophageal sphincter 16. Barrett's esophagus isan inflammatory disorder in which the stomach acids, bile acids andenzymes regurgitated from the stomach and duodenum enter into the loweresophagus causing damage to the esophageal mucosa. When this type ofretrograde flow occurs frequently enough, damage may occur to esophagealepithelial cells 18. In some cases the damage may lead to the alterationof the squamous cells, causing them to change into taller specializedcolumnar epithelial cells 20. This metaplastic change of the mucosalepithelium from squamous cells to columnar cells is called Barrett'sesophagus. Although some of the columnar cells may be benign, others mayresult in adenocarcinoma.

In one aspect, the present invention provides methods and systems forsizing the esophagus and treating columnar epithelium of selected sitesof the esophagus in order to mitigate more severe implications for thepatient. In many therapeutic procedures according to the presentinvention, the desired treatment effect is ablation of the tissue. Theterm “ablation” as used herein means thermal damage to the tissuecausing tissue or cell necrosis. However, some therapeutic proceduresmay have a desired treatment effect that falls short of ablation, e.g.some level of agitation or damage that is imparted to the tissue toinure a desired change in the cellular makeup of the tissue, rather thannecrosis of the tissue. With the present invention, a variety ofdifferent energy delivery devices can be utilized to create a treatmenteffect in a superficial layer of tissue, while preserving intact thefunction of deeper layers, as described hereafter.

Cell or tissue necrosis can be achieved with the use of energy, such asradiofrequency energy, at appropriate levels to accomplish ablation ofmucosal or submucosal level tissue, while substantially preservingmuscularis tissue. Such ablation is designed to remove the columnargrowths 20 from the portions of the esophagus 14 so affected.

As illustrated in a cross-sectional view in FIG. 2, the esophagus in itscollapsed, relaxed state does not form a perfect, cylindrical tube.Rather, the walls of the esophagus 14 undulate into a plurality offolds. In this state, the diameter of the esophagus is difficult todetermine, especially by use of visualization techniques such asultrasound or optical imaging. Additionally, uniform treatment of targettissue areas is also difficult because of the irregular surface contoursof the esophageal wall.

In one embodiment of the invention, as illustrated in FIGS. 2, 3 and 4and the flow chart of FIG. 5, a method is disclosed for utilizing asizing device to measure luminal dimensions. The sizing device 40 isfirst delivered to the treatment region in the body lumen, as shown atblock 70. For esophageal sizing as shown in FIG. 2, the esophagus 14will be in a relaxed or collapsed configuration during delivery of thesizing device. The sizing device 40 is in a collapsed configurationduring the delivery of the device to the treatment site in theesophagus. The low profile of the collapsed sizing device 40, as shownin FIG. 2, eases the delivery of the device into the esophagus andminimizes discomfort to the patient. Once the sizing device is orientedin the proper treatment area, an expansion fluid is injected into theballoon, as shown at block 72. The balloon is inflated until it engagesthe inside wall of the lumen, as shown in FIG. 3. During the infusion ofthe expansion medium, the extent of engagement of the balloon ismonitored, as well as the amount of expansion medium being injected intothe balloon, as shown by block 74. Once the balloon properly engages thelumen wall (shown at block 76), the final mass or volume of expansionmedium is recorded so that the internal dimension of the esophagus maybe calculated, shown at blocks 78, 82. The sizing balloon is thendeflated so that it can be readily removed from the treatment site,shown at block 80.

Referring to FIGS. 2, 3, 4, a device of the present invention comprisesa sizing device 40 for determining the dimensions of a treatment lumen.The device 40 has an expansion member 42 that is inserted into a lumenin a collapsed configuration and expanded upon proper placement at apre-selected treatment area. In a preferred configuration, the expansionmember 42 is a cylindrical balloon with a native diameter that isoversized so that it will be larger in its fully expanded configurationthan the expected diameter of the treatment lumen. The balloon 42comprises a thin, flexible, bladder made of a material such as polymer,for example polyimide, polyurethane, PET, or the like. The balloon isattached to a catheter sleeve 44, wherein the balloon is disposed on thedistal end 46 of the catheter sleeve for infusing an expansion mediuminto the balloon from an infusion source IS. Infusion source IS isconnected to an access port 50 of a y-connector located at the proximalend 48 of the catheter sleeve 44.

Ideally, the expansion medium comprises a compressible fluid, such asair. The expansion medium may alternatively comprise an incompressiblefluid, such as water, saline solution, or the like. Infusion of theexpansion medium into the sizing balloon may be accomplished by apositive displacement device such as a fluid-infusion pump or calibratedsyringe driven by stepper motor or by hand. Alternatively, for acompressible expansion medium, pressurized air or gas may also be used.In many embodiments, the sizing device also comprises a means fordetermining the amount of expansion fluid transferred to the balloon,such as a calibrated syringe. A mass or volume flow meter may be coupledto the fluid delivery source for simultaneously measuring the amount offluid in the balloon as it is inflated.

As the expansion medium is injected into balloon 42, the balloon expandsradially from its axis to engage the wall of the lumen. For esophagealtreatment, the walls of the esophagus 14 unfold to form a morecylindrical shape as balloon 42 expands, as illustrated in FIG. 3. Inthis configuration, internal diameter D1 of the esophagus 14 is readilycalculated based on the length L of the balloon and the measured amountof expansion medium inside the balloon. Balloon 42 is oversized so thatthe diameter D2 of the balloon when unrestrained and fully inflated islarger than the diameter of the balloon when constrained in the lumen.Although an inflatable balloon is generally preferred, the sizing membermay comprise a basket, plurality of struts, calipers, or the likeinstrument for determining the internal diameter of a tubular member.

Tests were performed to calculate the inside diameter of a member byusing volume flow measurements. Various types and sizes of tubes weretested by measuring the mass of air used to inflate an oversized bladderinside the tube. As shown in FIG. 7, the diameter of the tube can berepeatably estimated by measuring the volume of air delivered into theballoon.

In some embodiments of the invention, a pressure sensor may be coupledto the sizing device, wherein the extent of engagement is determined bythe internal pressure exerted from the expansion medium as measured bythe pressure sensor or visual verification. The pressure sensor maycomprise any device for determining the pressure inside a vessel, suchas a strain gauge. In FIG. 4, the pressure sensor PS is located ataccess port 52 at the proximal end of the catheter sleeve 44.Alternatively, the pressure sensor can be located inside the balloon 42.As the balloon expands to engage the wall of the lumen, the pressure inthe balloon increases as a result of the constraint on the balloon fromthe lumen wall. Because the balloon is oversized and not at its fullyextended diameter when contacting the lumen wall, the pressure in theballoon is equal to the contact force per unit area against the lumenwall. Therefore, the pressure inside the balloon is directlyproportional to the contact force on the lumen wall. Furthermore, theballoon may be expanded to apply pressure to the inside wall of thelumen, thereby causing the lumen to stretch. Generally, the sizingballoon will be inflated to a pressure corresponding to the desiredpressure for treatment of the lumen. For esophageal treatment, it isdesirable to expand the treatment device sufficiently to occlude thevasculature of the submucosa, including the arterial, capillary, orvenular vessels. The pressure to be exerted to do so should therefore begreater than the pressure exerted by such vessels, typically from 1 psigto 10 psig, and preferably from 4 psig to 7 psig.

In some embodiments, the measurement of the pressure inside the balloonmay be used to monitor the extent of engagement of the balloon with thelumen wall. Alternatively, the extent of engagement may be monitored bydetermining the expansion of the balloon via visual inspection with useof an endoscope, or by ultrasound, optical, or fluoroscopic imaging (notshown).

Tests were performed on different sized rigid tubes to calculate theamount of mass required to inflate an oversized balloon in a constrainedtube at various pressures. As shown in FIG. 8, the test results showed apredictable linear relationships between the measured inflated air massand the tube diameter for each pressure range tested.

As shown in the flow chart of FIG. 6, a method and system of the presentinvention is disclosed for treating a luminal tissue. Similar to themethod described in FIG. 5, a sizing device is used to calculate theinternal diameter of the lumen, as shown at block 84. The measurementobtained from the sizing device is then used to select a treatmentdevice from an array of different sized catheters, shown at block 86.The device is then inserted into the body lumen and delivered to thetreatment site, as shown at block 88. An expansion fluid is theninjected into the device by an infusion source like that of the sizingdevice as shown in block 90. Because the catheter is selected to have anouter diameter when fully expanded that appropriately distends theluminal wall, it is not necessary to monitor the expansion of thecatheter. However, the pressure and fluid volume of expansion mediumdelivered to the treatment device can be monitored as a precautionarymeasure, as shown in blocks 92 and 94. With the catheter properlyengaged to the luminal wall at the treatment site, energy, such as RFenergy, is delivered to the catheter for treatment of the luminaltissue, as shown at block 96. Once treatment has been administered, thecatheter is deflated for removal from the lumen as shown in block 98.

As illustrated in FIGS. 9 and 10, a treatment device 10 constructed inaccordance with the principles of the present invention, includes anelongated catheter sleeve 22, that is configured to be inserted into thebody in any of various ways selected by the medical provider. Fortreatment of the esophagus, the treatment device may be placed, (i)endoscopically, e.g. through esophagus 14, (ii) surgically or (iii) byother means.

When an endoscope (not shown) is used, catheter sleeve 22 can beinserted in the lumen of the endoscope, or catheter sleeve 22 can bepositioned on the outside of the endoscope. Alternately, an endoscopemay be used to visualize the pathway that catheter 22 should followduring placement. As well, catheter sleeve 22 can be inserted intoesophagus 14 after removal of the endoscope.

An electrode support 24 is provided and can be positioned at a distalend 26 of catheter sleeve 22 to provide appropriate energy for ablationas desired. Electrode support 24 has a plurality of electrode areasegments 32 attached to the surface of the support. The electrodes 32can be configured in an array 30 of various patterns to facilitate aspecific treatment by controlling the electrode size and spacing(electrode density). In various embodiments, electrode support 24 iscoupled to an energy source configured for powering the array 30 atlevels appropriate to provide the selectable ablation of tissue to apredetermined depth of tissue. The energy may be deliveredcircumferentially about the axis of the treatment device in a singlestep, i.e., all at one time. Alternatively, the energy may be deliveredto different circumferential and/or axial sections of the esophagealwall sequentially.

In many embodiments, the support 24 may comprise a flexible,non-distensible backing. For example, the support 24 may comprise of athin, rectangular sheet of polymer materials such as polyimide,polyester or other flexible thermoplastic or thermosetting polymer film.The support 24 may also comprise polymer covered materials, or othernonconductive materials. Additionally, the backing may include anelectrically insulating polymer, with an electro-conductive material,such as copper, deposited onto a surface so that an electrode patterncan be etched into the material to create an array of electrodes.

Electrode support 24 can be operated at a controlled distance from, orin direct contact with the wall of the tissue site. This can be achievedby coupling electrode support 24 to an expandable member 28, which has acylindrical configuration with a known, fixed length, and a diametersized to match at its expanded state the calculated diameter of theexpanded (not collapsed) lumen. Suitable expandable members include butare not limited to a balloon, non-compliant balloon, balloon with atapered geometry, cage, frame, basket, plurality of struts, expandablemember with a furled and an unfurled state, one or more springs, foam,bladder, backing material that expands to an expanded configuration whenunrestrained, and the like. For esophageal treatment, it is desirable toexpand the expandable member to distend the lumen sufficiently toocclude the vasculature of the submucosa, including the arterial,capillary, or venular vessels. The pressure to be exerted to do soshould therefore be greater than the pressure exerted by such vessels,typically from 1 psig to 10 psig, and preferably from 4 psig to 7 psig.Generally, the expandable member for the treatment device will beselected to match the diameter measured by the sizing device at thedesired pressure. Under this configuration, full expansion of theexpandable member will result in the a pressure that properly distendsthe luminal wall. In some embodiments, it may be desirable to employ apressure sensor or mass flow meter (not shown) as a precautionarymeasure so that over-distension of the lumen does not occur.

As shown in FIGS. 9 and 10, the electrode support 24 is wrapped aroundthe circumference of expandable member 28. In one system of the presentinvention, a plurality of expandable members can be provided wherein thediameter of the expandable member varies from 12 mm to 50 mm whenexpanded. Accordingly, the system may include a plurality of electrodesupports, each sized differently corresponding to the different sizedexpandable members. Alternatively, the electrode support 24 may beoversized to be at least large enough to cover the circumference of thelargest expandable member. In such a configuration, the electrodesupport overlaps itself as it is wrapped around the circumference of theexpandable member, similar to the electrode support of device 100illustrated in FIG. 11, discussed infra.

In another embodiment, expandable member 28 is utilized to deliver theablation energy itself. An important feature of this embodiment includesthe means by which the energy is transferred from distal end 26 toexpandable member 28. By way of illustration, one type of energydistribution that can be utilized is disclosed in U.S. Pat. No.5,713,942, incorporated herein by reference, in which an expandableballoon is connected to a power source, which provides radio frequencypower having the desired characteristics to selectively heat the targettissue to a desired temperature. Expandable member 28 may be constructedfrom electrically insulating polymer, with an electro-conductivematerial, such as copper, deposited onto a surface so that an electrodepattern can be etched into the material to create an array ofelectrodes.

Electrode support 24 can deliver a variety of different types of energyincluding but not limited to, radio frequency, microwave, ultrasonic,resistive heating, chemical, a heatable fluid, optical including withoutlimitation, ultraviolet, visible, infrared, collimated or noncollimated, coherent or incoherent, or other light energy, and the like.It will be appreciated that the energy, including but not limited tooptical, can be used in combination with one or more sensitizing agents.

The depth of treatment obtained with treatment device 10 can becontrolled by the selection of appropriate treatment parameters by theuser as described in the examples set forth herein. One importantparameter in controlling the depth of treatment is the electrode densityof the array 30. As the spacing between electrodes decreases, the depthof treatment of the affected tissue also decreases. Very close spacingof the electrodes assures that the current and resulting ohmic heatingin the tissue is limited to a very shallow depth so that injury andheating of the submucosal layer are minimized. For treatment ofesophageal tissue using RF energy, it may be desirable to have a widthof each RF electrode to be no more than, (i) 3 mm, (ii) 2 mm, (iii) 1 mm(iv) 0.5 mm or (v) 0.3 mm (vi) 0.1 mm and the like. Accordingly, it maybe desirable to have a spacing between adjacent RF electrodes to be nomore than, (i) 3 mm, (ii) 2 mm, (iii) 1 mm (iv) 0.5 mm or (v) 0.3 mm(vi) 0.1 mm and the like. The plurality of electrodes can be arranged insegments, with at least a portion of the segments being multiplexed. AnRF electrode between adjacent segments can be shared by each of adjacentsegments when multiplexed.

The electrode patterns of the present invention may be varied dependingon the length of the site to be treated, the depth of the mucosa andsubmucosa, in the case of the esophagus, at the site of treatment andother factors. The electrode pattern 30 may be aligned in axial ortraverse direction across the electrode support 24, or formed in alinear or non-linear parallel matrix or series of bipolar pairs ormonopolar electrodes. One or more different patterns may be coupled tovarious locations of expandable member 28. For example, an electrodearray, as illustrated in FIGS. 13( a) through 13(c), may comprise apattern of bipolar axial interlaced finger electrodes 68, six bipolarrings 62 with 2 mm separation, or monopolar rectangles 65 with 1 mmseparation. Other suitable RF electrode patterns which may be usedinclude, without limitation, those patterns shown in FIGS. 14( a)through 14(d) as 54, 56, 58 and 60, respectively. Pattern 54 is apattern of bipolar axial interlaced finger electrodes with 0.3 mmseparation. Pattern 56 includes monopolar bands with 0.3 mm separation.Pattern 60 includes bipolar rings with 0.3 mm separation. Pattern 58 iselectrodes in a pattern of undulating electrodes with 0.2548 mmseparation.

A probe sensor may also be used with the system of the present inventionto monitor and determine the depth of ablation. In one embodiment, oneor more sensors (not shown), including but not limited to thermal andthe like, can be included and associated with each electrode segment 32in order to monitor the temperature from each segment and then be usedfor control. The control can be by way of an open or closed loopfeedback system. In another embodiment, the electroconductive member canbe configured to permit transmission of microwave energy to the tissuesite. Treatment apparatus 10 can also include steerable and directionalcontrol devices, a probe sensor for accurately sensing depth ofablation, and the like.

Referring to FIG. 11, one embodiment of the invention comprises anelectrode deployment device 100 having an electrode support 110 furledaround the outside of an inflatable balloon 116 that is mounted on acatheter sleeve 118. Support 110 has an electrode array 112 etched onits surface, and is aligned between edges 120 that intersect the taperregion located at the distal and proximal ends of balloon 116. Support110 may be attached at a first end 122 to balloon 116 with an adhesive.The second end 124 of the support is furled around the balloon,overlapping the first end 122. Alternatively, support 110 may beretained in a compressed furled state around balloon 116 by an elasticband. In such a configuration, the adhesive need not be applied toattach first end 122 to balloon 116, thus allowing for rapid placementor exchange of the appropriately sized balloon 116 to match measurementsmade from the sizing device 10 illustrated in FIG. 4.

FIG. 12 shows a bottom view 150 and a top view 152 of the electrodearray 112 of support 110. In this embodiment, the array 112 has 20parallel bars, 0.25 mm wide, separated by gaps of 0.3 mm. The bars onthe circuit form twenty complete continuous rings around thecircumference of balloon 116. Electrode array 112 can be etched from alaminate consisting of copper on both sides of a polyimide substrate.One end of each copper bar has a small plated through hole 128, whichallows signals to be passed to these bars from 1 of 2 copper junctionblocks 156 and 158, respectively, on the back of the laminate. Onejunction block 156 is connected to all of the even numbered bars, whilethe other junction block 158 is connected to all of the odd numberedbars.

As shown in FIGS. 11 and 12, each junction block 156 and 158 is thenwired to a bundle of AWG wires 134. The wiring is external to balloon116, with the distal circuit wires affixed beneath the proximal circuit.Upon meeting the catheter sleeve of the device, these bundles 134 can besoldered to three litz wire bundles 136. One bundle 136 serves as acommon conductor for both circuits while the other two bundles 136 arewired individually to each of the two circuits. The litz wires areencompassed with heat shrink tubing along the entire length of thecatheter sleeve 118 of the device. Upon emerging from the proximal endof the catheter sleeve, each of these bundles 136 is individuallyinsulated with heat shrink tubing before terminating to a mini connectorplug 138. Under this configuration, power can be delivered to either orboth of the two bundles so that treatment can be administered to aspecific area along the array.

The y connector 142 at the proximal end of the catheter sleeve includesaccess ports for both the thru lumen 144 and the inflation lumen 146.The thru lumen spans the entire length of the balloon catheter and exitsthrough lumen tip 148 at the distal end of balloon 116. The inflationlumen 146 is coupled to balloon 116 so that the balloon can be inflatedby delivery of a liquid, gaseous solution such as air, or the like.

In some embodiments, for delivery of apparatus 100, support 110 istightly furled about deflated balloon 116 and placed with within asheath (not shown). During deployment, this sheath is retracted alongthe shaft to expose support 110. In alternative embodiments, an elasticmember (not shown) may be coupled to the support 110 to keep the supportfurled around balloon 116 during deployment of apparatus 100.

In order to ensure good contact between the esophageal wall andelectrode array 112, slight suction may be applied to the through lumentube to reduce the air pressure in the esophagus 14 distal to balloon116. The application of this slight suction can be simultaneouslyapplied to the portion of the esophagus 14 proximal to balloon 116. Thissuction causes the portion of the esophageal wall distended by balloon116 to be pulled against electrode arrays 112 located on balloon 116

Apparatus 100, illustrated in FIG. 11, is designed for use with the RFenergy methods as set forth herein. Electrode array 112 can be activatedwith approximately 300 watts of radio frequency power for the length oftime necessary to deliver an energy density per cm² from 1 J/cm² to 50J/cm². To determine the appropriate level of energy, the diameter of thelumen is evaluated so that the total treatment area can be calculated. Atypical treatment area will require total energy density per cm² rangingfrom 1 J/cm² to 50 J/cm².

In order to effectively ablate the mucosal lining of the esophagus andallow re-growth of a normal mucosal lining without creating damage tounderlying tissue structures, it is preferable to deliver theradiofrequency energy over a short time span in order to reduce theeffects of thermal conduction of energy to deeper tissue layers, therebycreating a “searing” effect. It is preferable to deliver theradiofrequency energy within a time span of less than 5 seconds. Anoptimal time for effective treatment is less than 1 second, andpreferably less than 0.5 second or 0.25 seconds. The lower bound on timemay be limited by the ability of the RF power source to deliver highpowers. Since the electrode area and consequently the tissue treatmentarea can be as much as several square centimeters, RF powers of severalhundred watts would be required in order to deliver the desired energydensity in short periods of time. This may pose a practical limitationon the lower limit of time. However, an RF power source configured todeliver a very short, high power, pulse of energy could be utilized.Using techniques similar to those used for flash lamp sources, or othertypes of capacitor discharge sources, a very high power, short pulse ofRF energy can be created. This would allow treatment times of a fewmsec. or less. While this type of approach is feasible, in practice amore conventional RF source with a power capability of several hundredwatts may be preferred.

The energy source may be manually controlled by the user and is adaptedto allow the user to select the appropriate treatment time and powersetting to obtain a controlled depth of ablation. The energy source canbe coupled to a controller (not shown), which may be a digital or analogcontroller for use with the energy source, including but not limited toan RF source, or a computer with software. When the computer controlleris used it can include a CPU coupled through a system bus. The systemmay include a keyboard, a disk drive, or other non volatile memorysystem, a display and other peripherals known in the art. A programmemory and a data memory will also be coupled to the bus.

In some embodiments of the present invention, systems and methods aredisclosed for treating luminal tissue with a single treatment devicethat variably expands to accommodate a number of different sized lumens.Preferably, the treatment device comprises a furled electrode supportthat variably engages the luminal wall while keeping the electrodedensity constant. Such approaches are described in detail in co-pendingapplication Ser. No. 10/754,444, published as U.S. publication no.2005/0171524, the full disclosure of which is incorporated herein byreference. For example, for the treatment device 100 shown in FIG. 11,which employs a variable exposed-length electrode array 112, balloon 116may be oversized with respect to the size of the lumen so that it can beexpanded to accommodate differing luminal dimensions from patient topatient. Measurements from sizing device 10 can be used to scale asneeded the desired power and energy settings to deliver the same powerand energy per unit area. These changes can be made either automaticallyor from user input to the RF power source. If different treatment depthsare desired, the geometry of electrode array 112 can be modified tocreate either a deeper or more superficial treatment region. Making theelectrodes of array 112 more narrow and spacing the electrodes closertogether reduces the treatment depth. Making the electrodes of array 112wider, and spacing the electrodes further apart, increases the depth ofthe treatment region. Non-uniform widths and spacings may be exploitedto achieve various treatment effects.

Referring to FIG. 15, the sizing device may be used as a method fordetermining the lumen diameter and wall compliance of one or moresections of the esophagus. A sizing device having an inflatable balloonlike that of device 40 illustrated in FIG. 5 is inserted into theesophagus in a compressed configuration and positioned at a locationwithin the esophagus, as shown at block 200. The balloon is theninflated with a compressible fluid so that the balloon engages theinside wall of the esophagus and distends the wall of the esophagus,shown at block 202. While the expansion medium is delivered to theballoon, the static pressure inside the balloon is monitored with apressure sensor and the amount of expansion medium delivered to theballoon is measured, shown at block 204. The pressure may be measured atthe infusion source with strain gauge or the like. Alternatively, thepressure can be measured at a location inside the balloon with amicrominiature pressure transducer or the like. The amount of expansionmedium delivered to the balloon may comprise a mass-flow meter or thelike. Once a first target pressure (P1) inside the balloon is achieved,a corresponding first mass or volume measurement (M1) is recorded, asshown at blocks 206 and 208. The values of P1 and M1 are used tocalculate the lumen diameter at pressure P1, using the relationshippreviously determined and shown in FIG. 8, block 200 of FIG. 15, orother equivalent means. Additional expansion medium is then delivered tothe balloon, and the static pressure and the total amount of expansionmedium within the balloon are monitored, shown at blocks 210 and 212.This continues until a second target pressure (P2) inside the balloon isachieved, and a corresponding second mass or volume measurement (M2) isrecorded, as shown at blocks 214 and 216. Calculation of the lumendiameter at pressure P2 is performed as previously described and shownin block 220. The sizing balloon is then deflated and then removed fromthe esophagus as shown in block 218. Target pressure values P1 and P2are generally set at values that cause the esophagus to distend, but notover-distend. Typical target pressure values range from 1 psig to 7psig, preferably 4 psig to 7 psig. Wall compliance of the esophagus isthen determined based on the variation in the calculated lumen diameterbetween a first measured pressure P1 and a second measured pressure P2,as shown in block 222.

While the exemplary embodiments have been described in some detail, byway of example and for clarity of understanding, those of skill in theart will recognize that a variety of modification, adaptations, andchanges may be employed. Hence, the scope of the present inventionshould be limited solely by the appending claims.

1. A method for treating the esophagus at a treatment locationcomprising a diseased mucosal lining, the method comprising: introducingan expandable sizing member at the treatment location within theesophagus; substantially unfolding surface contours of a wall of theesophagus at the treatment location by expanding the sizing member;measuring a substantially unfolded esophageal luminal dimension at thetreatment location while the sizing member retains the contours of thewall of the esophagus in a substantially unfolded condition; removingthe sizing member from the patient; selecting an electrode structurewith a pre-selected deployed state which corresponds to the measuredesophageal luminal dimension; after removal of the sizing member andwhile maintaining the sizing member outside of the patient, introducingand deploying the selected electrode structure to the pre-selecteddeployed state to engage the substantially unfolded esophageal wall atthe treatment location; and delivering energy to an electrode of theelectrode structure for treatment of a portion of the diseased mucosallining of the esophageal tissue at the treatment location.
 2. The methodfor treating the esophagus according to claim 1, wherein expanding thesizing member comprises inflating a sizing balloon by introducing anexpansion medium.
 3. The method for treating the esophagus according toclaim 2, wherein the expansion medium is a compressible fluid.
 4. Themethod for treating the esophagus according to claim 2, wherein theexpansion medium is an incompressible fluid.
 5. The method for treatingthe esophagus according to claim 1, wherein measuring comprisesdetermining the amount of an expansion medium introduced to the sizingballoon while it is inflated.
 6. The method for treating the esophagusaccording to claim 5, wherein determining the amount of expansion mediumcomprises measuring the mass of the expansion medium introduced to thesizing balloon.
 7. The method for treating the esophagus according toclaim 5, wherein determining the amount of expansion medium comprisesmeasuring the volume of the expansion medium introduced to the sizingballoon.
 8. The method for treating the esophagus according to claim 5,wherein determining the amount of expansion medium comprises measuringan internal pressure exerted from the expansion medium using a pressuresensor coupled to the sizing balloon.
 9. The method for treating theesophagus according to claim 8, wherein calculating further comprisesdetermining the esophageal luminal dimension based on the measuredamount of expansion medium introduced to the balloon at a givenpressure.
 10. The method for treating the esophagus according to claim1, wherein the selecting step comprises choosing one electrode structurefrom an inventory of devices having different electrode deploymentsizes.
 11. The method for treating the esophagus according to claim 1,wherein deploying the selected electrode structure comprises inflating aballoon configured to expand the electrode structure.
 12. The method fortreating the esophagus according to claim 11, wherein deploying theelectrode structure comprises inflating the balloon with an expansionmedium.
 13. The method for treating the esophagus according to claim 12,wherein deploying the selected electrode structure further comprisescontrolling inflation of the balloon to a pressure no greater than 7psig by sensing pressure using a pressure sensor.
 14. The method fortreating the esophagus according to claim 13, wherein the balloon isinflated to a pressure between 4 psig and 7 psig.
 15. The method fortreating the esophagus according to claim 1, wherein the selectedelectrode structure comprises an array of electrodes.
 16. The method fortreating the esophagus according to claim 15, wherein delivering energycomprises applying radiofrequency energy to tissue of the esophagusthrough the array of electrodes, wherein the array of electrodescomprises a multiplicity of parallel bipolar electrode pairs having awidth in the range from 0.1 mm to 3 mm, and are spaced-apart by adistance in the range from 0.1 mm to 3 mm.
 17. A method for treating thetissue of an esophagus at a treatment location proximal to the loweresophageal sphincter, the method comprising: introducing an expandablesizing member at the treatment location within the esophagus andproximal to the lower esophageal sphincter; substantially unfoldingsurface contours of a wall of the esophagus at the treatment location byexpanding the sizing member; measuring a substantially unfoldedesophageal luminal diameter at the treatment location; positioning anelectrode deployment device at the treatment location within theesophagus and proximal to the lower esophageal sphincter, wherein theelectrode deployment device has an electrode structure coupled to anexpansion member; deploying the expansion member to a size based oninformation obtained during the measuring step so as to engage theelectrode structure against a wall of the esophagus; and deliveringsufficient energy to the electrode structure for treatment of a diseasedesophageal tissue based on the unfolded esophageal luminal diameter atthe treatment location.
 18. The method for treating the esophagusaccording to claim 17, wherein expanding the sizing member comprisesinflating a sizing balloon by introducing an expansion medium.
 19. Themethod for treating the esophagus according to claim 18, wherein theexpansion medium is a compressible fluid.
 20. The method for treatingthe esophagus according to claim 18, wherein the expansion medium is anincompressible fluid.
 21. The method for treating the esophagusaccording to claim 17, wherein measuring comprises determining theamount of the expansion medium introduced to a sizing balloon while itis inflated.
 22. The method for treating the esophagus according toclaim 21, wherein determining the amount of expansion medium comprisesmeasuring the mass of the expansion medium introduced to the sizingballoon.
 23. The method for treating the esophagus according to claim21, wherein determining the amount of expansion medium comprisesmeasuring the volume of the expansion medium introduced to the sizingballoon.
 24. The method for treating the esophagus according to claim21, wherein determining the amount of expansion medium comprisesmeasuring an internal pressure exerted from the expansion medium using apressure sensor coupled to the sizing balloon.
 25. The method fortreating the esophagus according to claim 24, wherein calculatingfurther comprises determining the esophageal wall diameter based on themeasured amount of expansion medium inside the balloon at a givenpressure.
 26. The method for treating the esophagus according to claim17, wherein deploying the expansion member of the electrode deploymentdevice comprises inflating the expansion member, wherein the expansionmember comprises a balloon configured to expand to a range of diametersbetween 12 mm and 50 mm.
 27. The method for treating the esophagusaccording to claim 26, wherein deploying the expansion member comprisesinflating the balloon with an expansion medium.
 28. The method fortreating the esophagus according to claim 27, wherein inflating theexpansion member comprises inflating the balloon to a pressure nogreater than 10 psig.
 29. The method for treating the esophagusaccording to claim 28, wherein the balloon is inflated to a pressurebetween 4 psig and 7 psig.
 30. The method for treating the esophagusaccording to claim 17, wherein delivering energy comprises applyingradiofrequency energy to tissue of the body lumen through electrodes ofthe electrode structure, wherein the electrodes comprise a multiplicityof parallel bipolar electrode pairs having a width in the range from 0.1mm to 3 mm, and are spaced-apart by a distance in the range from 0.1 mmto 3 mm.
 31. The method for treating the esophagus according to claim17, the delivery step further comprising: delivering an energy densityin the range from 1 joules/cm² to 50 joules/cm² to the diseasedesophageal tissue.
 32. The method for treating the esophagus accordingto claim 17, wherein the delivery step is completed in less than 0.5seconds.